Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/29/1999
Publication Date: N/A
Citation: N/A Interpretive Summary: Soybean cyst nematode (SCN), Heterodera glycines, is a serious pest of soybean throughout soybean production areas in the United States. The nematode causes an annual production loss of $407 million. One important factor in long-term control of the nematode is to know how well the nematode reproduces on soybean grown in different farm environments. These environments include soils that differ in soil type, organic matter, pH, and fertility levels. These soils also contain populations of SCN that differ in their abilities to reproduce on both susceptible soybean and resistant soybean. This research showed SCN to reproduce better in southern areas of the midwest as opposed to more northern areas. Also, SCN-resistant cultivars in the northern areas were more consistent in their abilities to reduce SCN numbers than were resistant cultivars grown in more southern areas. Thus, SCN in more southern regions of the midwest has more genetic diversity and ability to reproduce on resistant cultivars. These results will be instrumental to soybean producers in order to make sure that SCN numbers are below the damage threshold before planting soybean following rotation with corn.
Technical Abstract: An experiment was conducted in Heterodera glycines-infected fields in 40 North Central United States environments (21 sites in 1994 and 19 sites in 1995) to assess reproduction of the nematode. Two resistant and two susceptible soybean cultivars from each of the Maturity Groups (MG) I through IV were grown at each site in 6.1 m by 4 row plots. Soil samples were collected from each plot at planting and harvest and processed at Iowa State University to determine H. glycines initial (Pi) and final (Pf) population densities as eggs per 100 cm**3 soil. Overall, reproduction was higher on MG III and IV susceptible cultivars than on those in MG I and II. Resistant MG I and II cultivars reduced nematode population densities more consistently than those in MG III and IV. Reproduction of the nematode was similar among sites within the same maturity zone (MZ), defined as the areas of best adaptation of the corresponding MG. Nonetheless, careful monitoring of nematode population densities is necessary to assess changes that occur over time in individual fields.